In fact, there’s already an example of this in the DCU. Batman appearing in Creature Commandos is exactly this. They don’t know who is playing Batman yet, nor what the specific story of his film will be, but they know they are going to make a Batman film. Batman is out there. So that’s why that got a tease.

James Gunn is unifying DC video games with films and TV, collaborating with Rocksteady and NetherRealm to create an interconnected DC Universe.

DC Studios co-CEO James Gunn has revealed that he has a plan for the universe, building to what sounds like a big finale. At a recent press event, Gunn shared that a six year plan has been mapped out for the DCU that will lead to an Avengers-style project (H/T Variety ). But, Gunn said, "each individual project works as its own thing".